[NOTICKET][doc] fix aggregate count operation when value_col is not specified

fix: 5 bug fixes on tabular executor

[KM-533] add table level schema, differentiate with chunk level. expand retrieval result with FK exploration

[KM-515][document] Make Query for Tabular Type (XLSX & CSV)

[KM-516][KM-517] add new feature; ai can now see table & column names that have fk relationship with retrieved result

[NOTICKET] db_executor: CTE DML check now walks entire AST root, schema: cast instead of string interpolation

[KM-512] connect query executor to user question. add logging for db_executor

[NOTICKET] rename file name, updated after uv sync

[KM-512] add Pydantic model the LLM fills via function calling in sql_query, and add same signature for db and tabular

[KM-512] create folder for querying from bd/tabular docs